大青杨对不同干旱胁迫强度的形态和生理响应

为了研究大青杨对干旱环境的耐受性，通过聚乙二醇( PEG-6000) 模拟干旱胁迫，对不同胁迫强度下大青杨的生长状态、生物量分配、生理生化应答特征进行测定分析。结果显示，随着干旱胁迫时间的延长和强度的增加，大青杨幼苗的苗高、地径生长量和生物量积累明显减少，说明干旱胁迫对叶片造成了明显的损伤。脯氨酸、可溶性蛋白、可溶性糖含量均呈现先上升再下降的趋势，且轻度胁迫比中度、重度胁迫变化幅度小。在胁迫前期和中期均高于对照，说明大青杨幼苗有一定的抗旱能力。在胁迫末期有低于对照的趋势，此时幼苗细胞、组织受到了不可逆转的伤害。大青杨叶片的净光合速率明显呈现双峰模式，受胁迫幼苗显著低于对照且到达峰值的时间不同。胁迫后幼苗的第一个峰值出现的时间比对照提前2 h。大青杨能够忍耐短时轻度的干旱胁迫环境，中度和重度干旱胁迫对大青杨幼苗期的生长和生理过程有显著影响。

To investigate the drought tolerance of Populus ussuriensis, we simulated drought stress using polyethylene glycol (PEG-6000), and measured and analyzed the growth status, biomass allocation, and physiological and biochemical response characteristics of Populus ussuriensis seedlings under different stress intensities. The results showed that with the extension of drought stress duration and the increase of stress intensity, the seedling height, ground diameter growth and biomass accumulation of Populus ussuriensis seedlings decreased significantly, indicating that drought stress caused obvious damage to the leaves. The contents of proline, soluble protein and soluble sugar all showed a trend of first increasing and then decreasing, and the change amplitude under mild drought stress was smaller than that under moderate and severe drought stress. They were higher than the control group in the early and middle stages of stress, indicating that Populus ussuriensis seedlings have certain drought resistance. However, they tended to be lower than the control group at the late stage of stress, when the cells and tissues of the seedlings suffered irreversible damage. The net photosynthetic rate of Populus ussuriensis leaves showed an obvious bimodal pattern, and the stressed seedlings were significantly lower than the control group, with different peak arrival times. The first peak of the stressed seedlings appeared 2 hours earlier than that of the control group. Populus ussuriensis can tolerate short-term mild drought stress environments, while moderate and severe drought stresses have significant effects on the growth and physiological processes of Populus ussuriensis at the seedling stage.